I have to recommend using the Brad Point Bits, and hard wood to get a good clean and smooth sided hole. A five ball block is big enough for any hunting purpose, and the wood should be at least as thick as the ball is wide. I prefer to make it thicker, so a groove can be routed out on the bottom side to fit over the muzzle of the gun to aid indexing the ball. Its just a nice touch that shooters seem to appreciate. You can sell them in raw wood, or finished or partly in each. I like to fill the holes with some kind of wood filler, such as shellac, so that any patch lube is not absorbed by the wood from the patching while the PRB sits in the loading block. I think an ebony stain and then a gloss finish makes a very nice presentation. For real pizzazz, try drilling a hold in the handle large enough to fit a brass sleeve, epozied into the handle, through which a length of leather latigo is run to carry the bullet block around the neck, or to attach to the possible bag strap. ( so they don't lose it! )